Definition - There are many ways in which a person's health in relation to their weight can be classified, but the most widely used method is body mass index (BMI).BMI is a measure of whether you're a healthy weight for your height. You can use the BMI healthy weight calculator to work out your score.For most adults:​

a BMI of 25 to 29.9 means you are considered overweight,

a BMI of 30 to 39.9 means you are considered obese,

a BMI of 40 or above means you are considered severely obese.

BMI is not used to definitively diagnose obesity – as people who are very muscular sometimes have a high BMI, without excess fat – but for most people, it can be a useful indication of whether they may be overweight.

A better measure of excess fat is waist circumference, and can be used as an additional measure in people who are overweight (with a BMI of 25 to 29.9) or moderately obese (with a BMI of 30 to 34.9).

Generally, men with a waist circumference of 94cm or more and women with a waist circumference of 80cm or more are more likely to develop obesity-related health problems.

Overall Numbers - Some recent WHO global estimates show that - click here to see the full fact sheet.

In 2014 over 600 million adults (18 years and over) were obese.

Overall, about 13% of the world’s adult population (11% of men and 15% of women) were obese in 2014.

The worldwide prevalence of obesity more than doubled between 1980 and 2014.

In 2013, 42 million children under the age of 5 were overweight or obese. Once considered a high-income country problem, overweight and obesity are now on the rise in low- and middle-income countries, particularly in urban settings. In developing countries with emerging economies (classified by the World Bank as lower- and middle-income countries) the rate of increase of childhood overweight and obesity has been more than 30% higher than that of developed countries.

Global Distribution - The mapbelow illustrates the following points ​about the global distribution of obesity. To open the host site for this map click here.

Obesity is highest in North America, North Africa and the Middle East, and many Pacific islands.

South Africa and Venezuela are also ‘hotspots’.

Levels in Europe and Latin America are similar — despite differences in levels of development.

That sub-Saharan Africa and Asia have the lowest prevalence. ​

The WHO produces a list of obesity for each country in the world (2014) - click here to open the webpage. This data can also be download as an excel file. A preview of this table can be seen below.

The WHO also produce an interactive map that show the percentage of obesity for these individual countries - click here to open this page. The map can be changed to see obesity for males and females. A preview of this map can be seen below.

Recent Developments - The graph below shows the highest and lowest levels of obesity and how they have changed over the last 30 years. To open the host site for this graph click here.

The graphs below show how obesity has changed in the United Kingdom. To open the host sites for these graphs click the links below.

Causes of Obesity - Obesity is generally caused by consuming more calories – particularly those in fatty and sugary foods – than you burn off through physical activity. The excess energy is then stored by the body as fat.

Obesity is an increasingly common problem, because many modern lifestyles often promote eating excessive amounts of cheap, high-calorie food and spending a lot of time sitting at desks, on sofas or in cars.

There are also some underlying health conditions that can occasionally contribute to weight gain, such as an underactive thyroid gland (hypothyroidism), although conditions such as this don’t usually cause weight problems if they are effectively controlled with medication.

The Impact of Health and Lifestyle - to tackle obesity is important because, in addition to causing obvious physical changes, it can lead to a number of serious and potentially life-threatening conditions, such as:

The Impact on Economic Development - The following is a list of how obesity may have an impact on economic development of a country;

The cost of treating obese people and associated diseases,

The cost of long term sick for companies and the government,

The cost of managing obesity crisis -education and prevention.

The following bullets contain background information about the NHS and expenditure of the United Kingdoms governments, along with actual examples of how obesity is having an effect on the economic development of the United Kingdom.

Treatment and Management - The best way to treat obesity is to eat a healthy, reduced-calorie diet and to exercise regularly. To do this you should:

eat a balanced, calorie-controlled diet as recommended by your GP or weight loss management health professional (such as a dietitian)

join a local weight loss group

take up activities such as fast walking, jogging, swimming or tennis for 150-300 minutes a week

eat slowly and avoid situations where you know you could be tempted to overeat

You may also benefit from psychological support from a trained healthcare professional, to help change the way you think about food and eating.

If lifestyle changes alone don't help you lose weight, a medication called orlistat may be recommended. If taken correctly, this medication works by reducing the amount of the fat you absorb during digestion. Your GP will know whether orlistat is suitable for you.

·Minimum nutritional levels set by the government for school providing meals.

·Vending machines in school can only contain healthy foods.

·Legal requirement for primary and secondary school to increase the allocation given to physical education lessons.

·Government sets up a UK Obesity Strategy which was published in January 2009. This set targets to reduce obesity.

·In 2009 attends to spend £75 million campaigning to reduce obesity rates in the UK.

·One of the main initiatives is the Change 4Life campaign.

·Another initiative was the – ‘be healthy beheard’ campaign.

NHS

·Pilot scheme with 500 people was set up and run by NHS with financial rewards (£500) if people lost weight.

·GPs to call up all people between 40 and 74 for a health consultation. If these people are overweight they will be prescribed weight management and exercise programmes. 2.25 million people will be called up every year and a repeat consultation arranged every 5 years.

·Educate people on a healthy life style through advertising campaigns. NHS spent £500,000 on two TV adverts warning children against having an unhealthy life style.

·NHS staff have been targeted to lose weight to set an example to the general public.

Private Sector

·Many major firms in the food industry have signed up to the Change4Life campaign.

·Tesco and Asda have signed up to offer promotions on healthy food which could include cut price vegetables and fruit.

·Some food companies label their products with the Guided Daily Amounts (GDA) compared with what the product contains.

·Some food companies use the traffic light system on their products.

·Pizza Hut and Burger King to display calories contained in their meals.

Individual

·They must make the conscious effort to try and change their life style and educate thereself into the dangerous of obesity for their health